The invention concerns a cylindrical inset forming a mixing chamber for a binary atomizing nozzle which is mounted within a nozzle housing and ahead of the nozzle discharge. A plurality of radial boreholes are provided. The nozzle is supplied, on one hand, with the liquid, for instance water, to be atomized, and, on the other hand, with the atomizing gas, for instance air. The liquid is fed axially into the inset and the gas is fed radially through the radial boreholes from an annular space surrounding the inset in the nozzle housing into the inset.
A binary atomizing nozzle with the stated features has been disclosed in the German Offenlegungschrift No. 26 27 880. The known nozzle design is characterized in that the inflow and flow rates of the two individual phases are selected in relation to the remaining state parameters and the common outlet flow cross-section of a mixing chamber. The discharge rate equals the inherent speed of sound of the binary mixture and upon leaving the mixing chamber the mixture undergoes an impulsive drop in pressure.
The German Gebrauchsmuster No. 82 25 742 discloses another nozzle of the initially cited type. The essential features of this known binary atomizing nozzle consist in the inside chamber of a nozzle-type inset flaring in its terminal region facing the mixing zone. Communicating boreholes are radial or essentially radial and are provided in the flaring area and lead to an enclosing, annular space shaped in the manner of Laval nozzle to supply the gas. The flaring terminal region of the inner chamber of the inset acts as a pre-mixing zone for part of the gaseous medium with the liquid medium. The annular space is designed so that a pressure head of the gaseous medium is formed in the area of the communicating boreholes.
In the known nozzles of the state of the art outlined above, the gas is fed into the mixing chamber through several apertures located in one plane (German Gebrauchsmuster No. 82 25 742) or in only two planes (German Offenlegungsschrift No. 26 27 880), in either case perpendicularly to the liquid flow. In order to achieve optimal mixing of both components, gas and liquid, when this kind of gas supply to the mixing chamber exists, the design requires considerable expenditure. Moreover, the number of gas feed boreholes is inherently severely restricted when they are arranged in the direction of flow on a common axial generatrix of the mixing inset. It was found in practice that when radial boreholes are arrayed too tightly against each other in the axial direction (direction of flow), the required good mixing of the two phases, gas and liquid, is not assured per se.